Proc. Fla. State HorL Soc. 98: 216-218. 1985.

STORAGE CHARACTERISTICS OF THREE CULTIVARS OFYELLOW ( PEPO L)

Mark Sherman 'Multipik' fruit do not express the streaky or mottled University of Florida, IFAS symptoms typical of WMV-2 infected fruit. Several grow Vegetable Crops Department ers adopted this cultivar, but buyer resistance developed Gainesville, FL 32611 in some markets because of a reportedly shorter "shelf- Gary W. Elmstrom life". University of Florida, IFAS The objective of this work was to compare the storage Leesburg Agricultural Research and Education Center characteristics of the 'Multipik' cultivar with those of other Leesburg, FL 32749 commonly grown yellowstraightneck summer squash. The Judith J. Allen major storage characteristics of commercial importance are University of Florida, IFAS appearance and weight loss. Vegetable Crops Department Gainesville, FL 32611 Materials and Methods

Squash were grown as part of the cultivar trials on Additional index words, precocious pigmentation gene B, Apopka fine sand at the Leesburg Agricultural Research watermelon mosaic virus-2, weight loss, appearance, chil and Education Center. In 1984, 'Multipik' and 'Goldbar' ling injury. were compared. The first harvest was on 27 Apr and the second was on 2 May. In 1985, 'Multipik' and 'Seneca But Abstract. 'Multipik', a yellow summer squash cultivar with the terbar' were compared. The first harvest was on 24 Apr gene B for precocious yellow fruit pigmentation, has a pro and the second harvest was on 29 Apr. 'Goldbar' and duction advantage when watermelon mosaic virus-2 is a 'Seneca Butterbar' are important cultivars that do not have problem. 'Multipik' fruit do not express the streaky or mottled precocious gene B. Fruit from both harvests in both years symptoms typical of virus infected fruit. However, buyer resis were of similar physiological age. tance to this cultivar developed in some markets because of Freshly harvested fruit were transported to Gainesville a reportedly shorter "shelf-life". Experiments in this study where they were washed and selected for uniformity in compared the storage characteristics of 'Multipik' and size prior to the storage tests. Fruit were stored at5° or 'Goldbar' in 1984 and 'Multipik' and 'Seneca Butter-bar7 in 10°C for up to 17 days in 1984 and 21 days in 1985. There 1985. 'Goldbar' and 'Seneca Butterbar' are important cul- were 3 replications of 10 fruit each, except for the 2nd tivars that do not have precocious gene B. Fruits were stored harvest in 1985 which had 5 fruit per replication. Weight at5° or 10°C for up to 17 days in 1984 and 21 days in 1985. loss was determined and fruit were rated for overall ap Weight loss was determined and fruit were rated for overall pearance on alternate days during the storage period. Ap appearance on alternate days during storage. 'Multipik' had pearance-was rated on a 5 point scale with 5 = excellent, a higher % weight loss and a lower overall appearance than no defects; 4 = good, slight defects; 3 = fair, defects defi the other cultivar in both years. Significant differences in % nitely detract from salability; 2 = poor, marketable only weight loss were evident after as little as two days storage. under unusual conditions; and 1 = not marketable. Exper Generally, ratings for overall appearance were not signific iments were factorials in a split split plot design with stor antly different until after a week or more of storage. Fruit age temperature as the main plot and time of storage as damage during harvest accelerated weight loss and visual the sub-plot (5). Analyses of variance and linear andnon deterioration for all three cultivars. linear regression analyses were performed using the Statis Production of , crookneck, straightneck, scal tical Analysis System (10). lop, acorn, and represented a $30.2 mil lion dollar farm value in Florida during the 1983-84 season Results and Discussion (6). The average price per bushel was $10.12 and yields 'Multipik' was more susceptible to water loss during averaged 177 bushels per acre. Potential yields for yellow storage than either 'Goldbar' in 1984 or 'Seneca Butterbar' summer squash are much higher (3,4). However, virus in 1985 (Fig. 1). Analyses yielded highly significantlinear infections can seriously reduce marketable yields. Adlerz regressions. The addition of a quadratic term did not im et al. (2) reported that the three most common potyviruses prove the fit and they were not significantly different from in L. plantings in Florida were watermelon zero. In both years fruit from the second harvest lost water mosaic virus-1 (WMV-1), watermelon mosaic virus-2 at a faster rate than fruit from the first harvest (Figs. 1 and (WMV-2), and zucchini yellow mosaic virus (ZYMV). 2). This difference between harvests can be attributed to Symptoms were most severe for ZYMV, intermediate for the greater physical damage evident on fruit from the sec WMV-1, and least severe for WMV-2. ond harvest in both years. Whether this damage occurred 'Multipik', a yellow summer squash cultivar with the on the plant or during harvest is unknown, but it under gene B for precocious yellow fruit color (12), has a produc scores the delicate nature of these fruit and the need for tion advantage when WMV-2 is a problem,although it has careful handling. no advantage when WMV-] or ZYMV are present (1). Hruschka (7) reported that yellow had an average weight loss of 15% without showing any Florida Agricultural Experiment Station Journal Series No. 6874. shrivel symptoms. Average weight loss ranged from 17.6

216 Proc. Fla. State HorL Soc. 98: 1985. 1ST HARVEST A 10 5°C 10 2ND HARVEST 10°C

0 MULTIPIK O MULTIPIK A GOLDBAR ~ 8 D SENECA BUTTERBAR * 8 — S6 6 7/

o O 4 LJJ

A*0 2

I | | | I I ! I I I I I I I i i i i 0 2 4 6 8 10 12 14 16 18 20 DAYS IN STORAGE i2r Fig. 2. Regression lines for weight loss of 'Multipik' and 'Seneca But- O MULTIPIK terbar' during storage at 5° and 10°C. Each point is the mean of three 10 SENECA BUTTERBAR replications. Data are for the first harvest, 1985.

0) (0 o

o

LU » I 1 1 I I \ 1 I I I I I I t I I I I I I I 2 2 4 6 8 10 12 14 16 18 20 5°C 10°C DAYS IN STORAGE O MULTIPIK Fig. 1. Regression lines for weight loss of yellow straightneck summer O SENECA BUTTERBAR squash during storage. A = 1984, 'Multipik' and 'Goldbar', both harvests. B = 1985, 'Multipik' and 'Seneca Butterbar', second harvest. Each point is the mean of 6 values. Data are combined for temperatures. I I I I I I I I 8 10 12 14 16 18 20

DAYS IN STORAGE to 31.1% for squash having slight to extremely severe shrivel symptoms, respectively (7). In our tests with yellow Fig. 3. Regression lines for appearance of'Multipik' and 'Seneca But terbar' during storage at 5° or 10°C. Appearance was rated on a 5 point straightneck squash, fruit exhibited severe shrivel scale with 5 = excellent, no defects; 4 = good, slight defects; 3 = fair, symptoms in the range of 6-8% weight loss. In terms of defects definitely detract from salability; 2 = poor, marketable only under shrivel, damage during harvest effectively cut the storage unusual circumstances; and 1 = not marketable. Each point is the mean life of squash in half even under good storage conditions. of three replications. Data are for the first harvest, 1985. All 3 cultivars lost more water during storage at 5°C when compared to 10°C. This was particularly apparent by the end of the 20-day storage at 5°C while 'Seneca But for 'Multipik' from the first harvest in 1985 (Fig. 2). One terbar' fruit still had an acceptable appearance (Fig. 3). reason for this difference was that the vapor pressure de Mencarelli et al. (8) reported that zucchini squash could be ficit (VPD) was greater in our 5° storage room. Relative optimally stored at 5°C, a temperature previously thought humidity ranged from 84-96% (mean = 91%) in the 5° to be below the critical temperature to induce chilling in storage room. In the 10°C storage relative humidity ranged jury. Our results for yellow straightneck and zucchini (data from 93-99% (mean = 97%). This difference in humidity not shown) indicate that 5°C is too low for Florida grown resulted in a VPD at 5°C that was about double the VPD summer squash. at 10°C. Overall our results confirm the suspicions of the buyers The VPD alone cannot account for the differences who resisted 'Multipik' because of a "shorter shelf-life". shown in Fig. 2. If the VPD were the only factor involved Squash are rarely handled carefully or stored under opti then the difference in water loss between 5° and 10°C stor mal conditions in commercial situations. Thus, the differ age would be the same for both cultivars. One explanation ences between 'Multipik' and the other cultivars in our for this may be related to chilling injury. The 'Multipik' studies may be exaggerated during commercial handling. cultivar appeared to be more susceptible to chilling injury. It is interesting to speculate on the reason(s) for these 'Multipik' fruit were severely discolored and unacceptable cultivar differences. Anatomical differences in cuticle

Proc. Fla. State Hort. Soc. 98: 1985. 217 thickness, stomatal size and frequency, and trichome fre Zucchini yellow mosaic virus: a pathogen of squash and other cucur quency and structure may all have an influence on water bits in Florida. Proc. Fla. State Hort. Soc. 96:72-74. 3. Elmstrom, G. W. 1981. Summer squash-yellow variety trial results- loss (13). We have undertaken microscopic studies to deter Leesburg, p. 40. In: M. B. Lazin (ed.) Vegetable variety trial results mine if these anatomical factors are involved. The preco in Florida for 1981. Circ. S-304. Agr. Expt. Sta., Univ. Fla. cious yellow gene B in 'Multipik' is known to be highly 4. Elmstrom, G. W. 1982. Yellow summer squash trial, p. 47. In: J. M. pleiotropic (11, 12). A number of negative secondary ef White (ed.). Vegetable variety trial results in Florida for 1978-1979- fects have been reported. These include leaf-yellowing, 1980. Circ. S-289. Agr. Expt. Sta., Univ. Fla. 5. Federer, W. T. 1967. Experimental design theory and practice. Ox lower yields, and poor seed production (11, 12). These ford and IBH Publishing Co., New Delhi. secondary effects may or may not be expressed depending 6. Florida Crop and Livestock Reporting Service. 1985. Vegetable sum on the genetic background. Paris et al. (9) reported that a mary 1984. Fla. Agr. Stat. Orlando, Fla. precocious yellow zucchini cultivar 'Goldy' was capable of 7. Hruschka, H. W. 1977. Postharvest weight loss and shrivel in five fruits and vegetables. U.S. Dept. Agr. MRR. 1059. producing the yield and yield quality (grade) of green- 8. Mencarelli, F., W. J. Lipton, and S. J. Peterson. 1983. Responses of fruited zucchini cultivars. Schaffer and Boyer (11) found 'Zucchini' squash to storage in low-Oa atmospheres at chilling and little effect of gene B in fruit development in 'Early Prolific' nonchilling temperatures. J. Amer. Soc. Hort. Sci. 108:884-890. background. Our results limit us to discussion of between- 9. Paris, H. S., Z. Karchi, H. Nerson, and Y. Burger. 1983. Yield and cultivar differences. A comparison of isogenic lines would yield quality in precocious yellow zucchini cultivars. HortScience 18:724-726. be worthwhile to determine the possible effects of gene B 10. SAS Institute Inc. 1982. SAS user's guide: statistics, 1982 edition. on water loss and storability. SAS Institute Inc. Cary, NC. 11. Schaffer, A. A. and C. D. Boyer. 1984. The influence of gene B on Literature Cited fruit development in Cucurbila pepo. J. Amer. Soc. Hort. Sci. 109:432- 437. 1. Acllerz, W. C, G. W. Elmstrom, and D. E. Purcifull. 1985. Response 12. Shifriss, O. 1981. Origin, expression, and significance of gene B in of 'Multipik' squash to mosaic virus infection. HortScience 20:892- Cucurbila pepo L. J. Amer. Soc. Hort. Sci. 106:220-232. 893. 13. Showalter, R. K. 1980. Postharvest water loss control for vegetables. 2. Acllerz, W. C, D. E. Purcifull, G. W. Simone, and E. Hiebert. 1983. Vegetable Crops Fact Sheet, VC-28. Fla. Coop. Ext. Ser.

Proc. Fla. State Hort. Soc. 98: 218-219. 1985.

CALCIUM DETERMINATION IN CITRUS PULP WASH—A COMPARISON OF A COLORIMETRIC PROCEDURE WITH ATOMIC ABSORPTION SPECTROPHOTOMETRY

Richard L. Coleman, Mary S. Saunders and they were compared systematically (3). Our experience and Robert A. Baker results comparing these methods are the subject of this

U. S. Citrus &f Subtropical Products Laboratory2 report. P. 0. Box 1909 Winter Haven, Florida 33883-1909 Materials and Methods Abstract. Two methods of calcium determination, a commer The atomic absorption spectrophotometer (AA) was a cial colorimetric procedure and atomic absorption, were Perkin Elmer Model 372 using acetylene and air. Samples evaluated for routine laboratory use on citrus products and (3 ml) were prepared by the following methods: 1) unal other materials. Samples tested included commercial calcium tered samples were aspirated directly into the AA flame; standards, well and process water, and serial dilutions of cit 2) lanthanum was added to reduce interference from phos rus pulp wash. Satisfactory results on citrus pulp wash phates, and samples were aspirated into the AA flame; 3) samples could not be obtained with atomic absorption with samples were ashed at 500°C, extracted with HC1, and out the additional steps of ashing and redissolving in dilute treated with lanthanum before aspiration; or 4) samples acid. The colorimetric procedure cost less than the atomic ab were ashed at 900°C, extracted with HC1, and treated with sorption method and gave results which were as accurate. lanthanum before aspiration. All AA samples were pre Some citrus and other drink processors need to carry pared and analyzed in a commercial analytical laboratory. out a few calcium determinations on various samples inter (Applied Agricultural Research, Inc., Lakeland, Fla.). mittently. A comparison of available calcium determina Colorimetric determination of total calcium was carried tion methods was undertaken to find the most practical out using a commercial analytical kit (Calcium Determina means for determining calcium content in citrus products. tion Kit No. 586, Sigma Chemical Co., St. Louis, Mo.). Two methods were selected as least laborious and least This determination is based on calcium's reaction with cre- costly, yet reasonably accurate. These were atomic absorp solphthalein complexone to form a purple color with a tion spectrophotometry and a colorimetric procedure and maximum absorption at 575 nm. A Bausch & Lomb Spec- tronic 20 with standardized test tubes was used to read 'Private Consultant. 1102 East Magnolia Drive, Tallahassee, FL 32301 color intensity as absorbence at 575 nm. Double deionized -South Atlantic Area, U. S. Dept. Agr., Agr. Res. Serv. water, prepared by use of two deionization systems (Mitco Mention of a trademark or propriety product is for identification only Water Laboratories, Inc., Auburndale, Fl., and Cole- and does not imply an endorsement or warranty of the product by the U. S. Department of Agriculture over other products which may also be Parmer Instrument Co., Chicago, II.), was used in all stand suitable. ards and dilutions.

218 Proc. Fla. State Hort. Soc. 98: 1985.